A golf caddy who got into a row with a tractor driver on the course at Singapore Island Country Club hit him over the head with a club.
Selamat Satli, 65, swung the sand wedge at nursery worker Felix Joseph, 33, who he believed had been "staring" at him.
Selamat was jailed for four weeks yesterday after he pleaded guilty to an amended charge of causing hurt.
Mr Joseph, a Malaysian, was left with a 2cm cut on his forehead from the incident, which took place at around 1pm on Dec 15 last year.
He had been driving a tractor when Selamat approached him and asked him why he was staring at him. Mr Joseph, who was wearing sunglasses, denied doing so before the pair began quarrelling and Selamat hit him with the club.
Mr Joseph, who felt blood on his forehead, pushed Selamat away and ran to the nearest store and informed the management of the incident.
Mr Joseph was given three days' medical leave.
Selamat's lawyer said he had since lost his job, was remorseful and deeply regretted causing hurt to Mr Joseph.
The maximum penalty for causing hurt is two years' jail and a $5,000 fine.